The present invention relates to a communication apparatus and an operation method thereof. More particularly, the invention relates to a technology that effectively enables communication circuit operation during wireless charging of a battery mounted on a communication apparatus and prevents destruction of the communication circuit during a period to charge a secondary cell.
According to a related art technology, an IC card is mounted with a semiconductor integrated circuit and an antenna coil. To supply power for the IC card, the antenna coil receives an RF signal from a read/write apparatus referred to as a card reader/writer and a rectifier circuit rectifies the RF signal. The IC card having no power supply is widely used for automatic ticket systems, electronic money, and commodity distribution management. The IC card is also referred to as an RFID card because the IC card is RF-powered and stores unique identification information (ID information) in built-in nonvolatile memory. The IC card targeted for automatic ticket systems and electronic money uses Near Field Communication (NFC) using the RF frequency of 13.56 MHz.
On the other hand, a wireless charging system is also used on the increase. A potable device such as a smartphone can be charged when it is just placed on a special charging table without the need to couple a power cable to the portable device. The wireless charging system satisfies the need for large power consumption of smartphones as multifunctional mobile telephones. Smartphones have high affinity with the Internet and provide multifunctional mobile telephones that are based on personal computer functions and are provided with PDA capabilities in addition to telephone and e-mail capabilities. The wireless charging system is based on the Qi international standard developed by the Wireless Power Consortium (WPC). A transmission device and a reception device each have a coil to enable power supply to the reception device from the transmission device according to electromagnetic induction. The wireless charging system advantageously eliminates the need to plug or unplug a power connector for charging and omits operation of opening and closing a power supply connector cover on a portable device.
According to FIG. 2 and the related disclosure in patent document 1, the NFC is performed between a port device and a mobile device. The port device performs non-contact power transfer to charge a secondary cell (battery) of the mobile device. The mobile device includes an NFC induction coil and a charging induction coil. The NFC induction coil is coupled to an NFC chip. The charging induction coil is coupled to a charging power reception portion, a charge controller, and a secondary cell. The port device includes an NFC induction coil and a charging induction coil. The NFC induction coil is coupled to an NFC chip. The charging induction coil is coupled to a charging power supply portion.
According to FIG. 7 and the related disclosure in patent document 1, another non-contact power transfer system is described. The NFC is performed between the port device and the mobile device. The port device charges the secondary cell of the mobile device. The mobile device includes one induction coil used for the NFC and charging. The induction coil is coupled to a circuit selector. The circuit selector is coupled to the NFC chip and the charging power reception portion. The circuit selector selects one of the NFC chip and the charging power reception portion. The selected one is coupled to the induction coil through the circuit selector. The port device includes one induction coil used for the NFC and charging. The induction coil is coupled to a circuit selector. The circuit selector is coupled to the NFC chip and a charging power supply portion. The circuit selector selects one of the NFC chip and the charging power supply portion. The selected one is coupled to the induction coil through the circuit selector.
Patent Document 1: Japanese Unexamined Patent Publication No. 2009-253649